SYLLIDAE 133 



10 mm. in length. In some specimens traces of longitudinal dark markings are visible 

 on each side of the body just above the feet. The head is rounded and the two pairs of 

 eyes are almost contiguous. The tentacles, tentacular cirri and the dorsal cirrus of the 

 I St chaetiger are all very long and indistinctly annulated. The normal dorsal cirri are 

 smooth, short and stumpy, and are equal in length to about half the breadth of the body. 

 The pharynx extends to about the 8th chaetiger and the proventriculus to about the 

 1 2th. The pharynx appears to be unarmed and runs past the mouth of the proventriculus, 

 looping back to enter it. The bristles are clearly bidentate with a very well-developed 

 second tooth, so much so that the second tooth is as large as, if not larger than the apical 

 tooth. 



Bayonet bristles are present, but only discoverable under a very high magnification. 



Polybostrichus 

 Among these specimens there was a single ripe male. It measures about 4 mm. in 

 length for 28 chaetigers, of which the first six are unmodified. The head is round and 

 deeply notched in front and the rather slender bifid palps are turned backwards at the 

 sides in a manner that recalls the anterior tentacles of the Tomopterids. There are two 

 pairs of red eyes, a dorsal and a ventral, the ventral being considerably the larger. 

 Behind the dorsal eyes there is a minute pair of lateral tentacles. The median tentacle is 

 about the same length as the palps and reaches back to about the loth chaetiger. The 

 dorsal tentacular cirri are very long and the single remaining ventral tentacular cirrus 

 is a very slender filiform process about as long as the body is broad. All the modified 

 segments bear long swimming bristles. 



Polybostrichus sp..? (Fig. 23). 

 Occurrence. St. WS 832 (i). 



Description. The specimen measures 9 mm. by i mm. for 64 chaetigers, of which 

 the first 14 and the last 20 are unmodified. The colour is a pale brown and the head 

 appendages are white except for the median tentacle 

 and the dorsal cirri of the ist chaetiger, which are 

 also brown but paler than the body. The head is 

 rather longer than broad and the very wide, flattened 

 proximal areas of the modified, bifid palps are in 

 contact at their base. There are the usual two pairs 

 of large eyes, a dorsal and a ventral. At the inner and 1 



hinder corners of the dorsal eyes is a pair of small, ^'g- 23- Polybostrichus sp. Foot with 

 slender lateral tentacles, and behind these medially ««''"™"g bristles; dorsal cirrus 



■' omitted. 



is a large, stout median tentacle reaching back to 



the end of the anterior unmodified region. Squeezed in at the sides between the head 

 and the ist chaetiger, there are two pairs of slender tentacular cirri, the dorsal about 

 twice the length of the ventral. The dorsal cirri of the ist chaetiger are relatively 

 enormous and reach back to about the 20th chaetiger. The dorsal cirri of the following 

 three or four chaetigers are much smaller and equal in length the dorsal tentacular 



